Method and apparatus for producing data storage media

ABSTRACT

In one embodiment, the method for producing a stamper, comprises: forming a nickel plated substrate having desired surface features on one side; disposing a managed heat transfer layer on a second side of said substrate; forming a thickness of said managed heat transfer layer having a variation of less than about 5%; and altering said exposed surface of said managed heat transfer layer. Also disclosed are a method and apparatus for producing data storage media.

BACKGROUND OF THE INVENTION

[0001] Various types of molds have long been in use for preparingoptical discs from thermoplastic resins. Molds for these purposes aretypically manufactured from metal or a similar material having highthermal conductivity. For most purposes, high thermal conductivity isdesirable since it permits the resin in the mold to cool rapidly,shortening the molding cycle time. At times, however, cooling is sorapid that the resin freezes instantaneously at the mold surface uponintroduction into the mold, forming a thin solid layer which, especiallyif is contains a filler, can create rough surfaces, voids, porosity andhigh levels or residual stress and orientation. In an optical disc, suchimperfections impede the optical properties and decrease or eliminatethe performance of the optical disc.

[0002] Therefore, in an injection molding of compact discs, for audio,video, or computer data storage and retrieval applications, heattransfer through the mold has a strong effect on molding time and discattributes such as birefringence, flatness, and accuracy of featurereplication.

[0003] One method for affecting heat transfer and improving the cycletime during injection molding is known as the technique of managed heattransfer (MHT). The basic principle of managed heat transfer is applyinga passive thermal insulating layer to the mold to control the transientheat transfer between molten resin materials and the mold surfacesduring the injection molding. The insulating layer comprises materialshaving both low thermal diffusivity and conductivity, thus slowing thecooling of the molded resin, and good resistance to high temperaturedegradation, permitting use in a mold maintained at high temperatures.For improving mechanical strength, abrasion resistance, oxidationresistance and thermal conductivity, at least one skin layer may bebonded to the insulating layer.

[0004] Another method for affecting heat transfer is forming a syntheticresin layer on a stamper by coating or lamination before the stamper isplaced on a core molding surface of a metal mold.

[0005] The use of a heat transfer managing layer (HTM layer) such as thethermal insulating layer and the synthetic resin layer is desirable soas to cause a minimal change in the size and shape of a molding tool andequipment. However, requirements of optical clarity, surface morphology,and replication of surface features of submicron dimensions are verystringent for optical discs. Therefore, common insulating materials,which do not provide a smooth enough surface, are not stable for longperiods at the mold temperature, or cannot withstand the repeatedapplication of high pressure during the molding process, should beavoided.

[0006] It is also difficult to apply a thick polymer coating over a 6inch-diameter surface without defects such as particles or bubblesgetting into the film surface. Particles may be generated during thespin coating process as excess materials are spun off the stamper.Particles or bubbles in the coating forms “high” spots on the surface ofthe heat transfer managing layer, which causes dimples in the moldeddisc, potentially forming a defective track area.

[0007] Moreover, after applying the managing heat transfer layer to thestamper, the stampers are typically punched to a final dimensionrequired for mounting onto an injection molding equipment. This punchingor trimming process also shears the polymer coating, which, if brittle,can deposit particles in the surface of the layer. These may becomestatically attached to the polymer surface, and are not easily removed.The punch process may also leave a raised lip around the shearedperimeter, making mounting onto the molding machine more difficult.

SUMMARY OF THE INVENTION

[0008] It is therefore desirable to provide an apparatus, stamper, andmethod for manufacturing data storage media. In one embodiment, themethod for manufacturing data storage media comprises: disposing amanaged heat transfer layer in operable communication with a secondsurface of a stamper, wherein a first surface of said stamper comprisessurface features, wherein an exposed surface of said managed heattransfer layer has been altered by a method selected from the groupconsisting of chemically, mechanically, or a combination thereof;disposing the stamper in a mold with at least a portion of said exposedsurface disposed in operable communication with a mold half; injecting amolten plastic into said mold; cooling the plastic to form said datastorage media; and releasing said data storage media from said mold

[0009] In one embodiment, the molding apparatus for producing datastorage media comprises: a stamper comprising a managed heat transferlayer, wherein a first surface of said stamper comprises surfacefeatures, and wherein an exposed surface of said managed heat transferlayer has been altered by a method selected from the group consisting ofchemically, mechanically, or a combination thereof, and has a thicknessvariation of less than about 5%; and a support for receiving the stamperby operable communication with said managed heat transfer layer.

[0010] In one embodiment, the method for producing a stamper, comprises:forming a nickel plated substrate having desired surface features on oneside; disposing a managed heat transfer layer on a second side of saidsubstrate; forming a thickness of said managed heat transfer layerhaving a variation of less than about 5%; and altering an exposedsurface of said managed heat transfer layer, wherein said altering is bya method selected from the group consisting of chemically altering,mechanically altering, or a combination thereof.

[0011] The above described and other features are exemplified by thefollowing figure and detailed description.

BRIEF DESCRIPTION OF THE DRAWING

[0012] Referring now to the figure, in which:

[0013]FIG. 1 is a sectional side view of one embodiment of an injectionmold.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] Managed heat transfer layer can be used in injection molding andinjection-compression molding processes as layers disposed on thebackside of the stamper in order to inhibit uncontrolled cooling of themolten material. Upon contacting the stamper, the molten materialinjected into the mold rapidly cools. If the rate of cooling is notmanaged, the resultant article can possess defects such as peeling,cracking, and areas of increased stress. The employment of a managedheat transfer layer on the back-side of the stamper (i.e., the sideopposite the surface features and molten material contact) can controlthe rate of heat dissipation from the molten material, thereby improvingthe resultant article. Managed heat transfer layers are discussed incommonly assigned U.S. Pat. No. 6,146,588, which is incorporated hereinby reference.

[0015] In order to further enhance the advantages attained by theemployment of the managed heat transfer layer, various treatments can beemployed. These treatments include: processing the managed heat transferlayer (e.g., via polishing, reactive ion etching (RIE), surface lapping,combinations comprising at least one of these treatments, and the like)to attain a substantially uniform thickness and flatness; extending thelife of the managed heat transfer layer and/or the life of the stamper;chemically altering the surface of the managed heat transfer layerand/or applying a coating over the managed heat transfer layer, e.g., toinhibit adhesion to the adjacent mold half; and/or alter the coefficientof friction, at least in specified areas of the stamper to enhancevacuum adhesion to the mold in the clamping area. Good adhesion isdesirable in the clamping area, but not in its molding area where thestamper presses against the mirror block. In this area, low friction isdesirable to reduce the amount of abrasion the polymer receives witheach stamping cycle.

[0016] Surface imperfections on the managed heat transfer layer cantranslate through the stamper to the article during the molding processcreating random imperfections on the article surface and possiblyforming a defective article (e.g., an unreadable optical disk).Similarly, nonuniformity of the managed heat transfer layer can causeuneven transfer of the stamper surface features to the article,similarly causing imperfections. Consequently, the managed heat transferlayer preferably has a substantially uniform thickness, i.e., athickness that varies less than about 5% across the entire surface. Morepreferably, the thickness varies less than about 3%, with a thicknessvariation of less than about 1% even more preferred, and a variation ofless than about 0.5% especially preferred. For example, the managed heattransfer layer preferablyhas a local (i.e., across a 1 centimeter square(cm²) area) flatness (i.e., thickness variation), of less than about 75nanometers (nm), with less than about 50 nm more preferred, and lessthan about 25 nm especially preferred.

[0017] Substantially uniform thickness can be attained by surfacelapping using a grinding machine and very fine grit paper, i.e., gritpaper having a grit particle size of less than or equal to about 9micrometers. A particle size of less than or equal to about 5micrometers is preferred, with a grit particle size of less than orequal to about 3 micrometers is preferred.

[0018] Surface lapping, or finishing, both remove slight amounts ofmaterial preferably starting from the “high” spots on the polymercoating. This is controlled by the hardness of the support material usedto press the sandpaper down on the substrate. A “soft” material wouldconform to the existing surface, making it more difficult to removemicrowaviness. A “hard” sandpaper backing would be better suited toremove surface defects (high spots) and surface microwaviness.

[0019] Similar to initially forming a substrate comprising asubstantially uniform thickness, it is also preferred to retain theuniform thickness, free of surface defects, e.g., peeling, particles, ororange peel, during the use of the stamper. By removing surface defectssuch as peeling, which can adversely affect the electrical performanceand aesthetics of the finished article (e.g., data storage media, andthe like), the life of the managed heat transfer layer can be extended.For example, a typical managed heat transfer layer has a life of about50,000 shots or less, by removing the peeling, the life can be extendedto about 100,000 shots or more, with a life of about 200,000 shots orgreater readily attainable.

[0020] Removal of the peeling can be attained by a polishing or surfacelapping process that removes about 2 micrometers (μm) of material orless, with removal of about 1 μm or less preferred, and removal of about0.5 μm or less especially preferred. Such limited removal of materialcan allow re-flattening of the managed heat transfer layer withoutreducing its effectiveness in managing the heat transfer.

[0021] In addition to extending the life of the managed heat transferlayer via removal of peeling, life extension can be attained by reducingadhesion of a used managed heat transfer layer to the adjacent moldhalf, and by improving friction and wear properties of the managed heattransfer layer. Essentially, after a period of employment of the managedheat transfer layer in molding equipment, the layer can adhere to theadjacent mold half, e.g., the mirror block on the molding equipment,resulting in damage to the heat transfer layer and mirror block uponremoval of the stamper and managed heat transfer layer.

[0022] Reduction of adhesion to the molding equipment, as well asreduced friction and improved wear, can be attained by chemicallyaltering the surface of the managed heat transfer layer that interfaceswith the mold half. Chemically altering the surface can comprisechanging, e.g., reducing, the surface polymer(s) chain length, and/orchemically reacting the surface polymer(s) with another material tochange the chemical composition thereof. Chemical alteration can beaccomplished via a chemical and/or plasma process. A chemical processcan comprise exposing the surface to an aqueous caustic solution (e.g.,an aqueous solution of an alkali or alkaline earth metal hydroxide,carbonate, or a combination comprising at least one of the foregoingsolutions, such as potassium carbonate, barium hydroxide, potassiumhydroxide, and the like) to reduce the polymer length, surface modulus,and hardness. For example, a polyimide managed heat transfer layer canbe exposed to 2 wt % potassium hydroxide dissolved in and 80/20 mixtureof ethanol and water to remove about 1 micrometer/minute (μm/min) of thepolyimide coating. After etching, modulus for the polyimide surface isabout 100 kilopounds per square inch (Kpsi) vs. 400 Kpsi for that of thebulk.

[0023] Alternatively, plasma or reactive ion etch can be employed tochange the surface properties of the managed heat transfer layer.Parameters controlling reactive ion etching include the type andconcentration of gas(es) present during the plasma process, theoperating conditions that include temperature, pressure, power andfrequency, and the chamber materials that can comprise metal, glass,and/or plastics such as tetrafluoroethylene fluorocarbon polymers (e.g.,Teflon). Exposure of a managed heat transfer layer to the reactive ionetch chemistry can change its surface chemistry to provide moredesirable properties. The reactive ion etching can be a dry etching,which breaks polymer chains and volatilizes them resulting in slowetching of the polymer, leaving a composite managed heat transfer layerhaving a surface with low weight average molecular weight (Mw) chainspresent and thus lower modulus than that found in the bulk of the layer,or it can fluorinate areas on the polymer chain, greatly reducingfrictional wear on the surface during subsequent use in moldingequipment.

[0024] Generally, a plasma reactive ion etching system employs a gassuch as oxygen (O₂), chlorine (Cl₂), hydrochloric acid (HCl),fluorocarbons (e.g., Freong, CF₄, CHF₃, and the like), nitrogen (N₂),nitrogen oxide (N₂O), argon (Ar), boron trichloride (BCl₃), hydrogen(H₂), sulfur hexafluoride (SF₆), and the like, as well as ions, reactionproducts, and combinations comprising at least one of the foregoinggases. For example, oxygen can be used in a reactive ion etch system toetch organic polymers. The plasma dissociates the oxygen into ions thatreadily oxidize organic material it contacts with into volatilecompounds such as carbon dioxide, water, and nitric oxide. In anotherexample, a polyimide managed heat transfer layer can be exposed to afluorine ambient, such as trifluoromethane (CHF₃) plasma, which can becontrolled to leave a fluorinated polymer layer on the polyimide toreduce surface adhesion and friction to the molding equipment.

[0025] Reactive ion etch systems generally consist of a vacuum chambercontaining parallel plate electrodes, the cathode being powered by an rfgenerator at a frequency sufficient to form the plasma (e.g., for mostgases, typically at a frequency of about 13.56 MHz), while the secondelectrode, or anode, is grounded. During etching, substrates are placedon the cathode, the chamber is evacuated and gases are introduced andregulated at low pressure, typically less than 1 Torr. By controllingthe pressure, power and bias voltage on the cathode, RIE systems canetch a pattern either isotropically, that is, in all directions at andequal rate, or anisotropically, which means it predominately etchesvertically, maintaining the original pattern width.

[0026] Alternative, or in addition, to chemically altering the surfaceof the managed heat transfer layer, friction and adhesion can beadjusted by employing a lubricant, either in the managed heat transferlayer and/or as a coating or film on the surface of the managed heattransfer layer, between the managed heat transfer layer and the moldingequipment. Various layers that can be deposited with a substantiallyuniform thickness, will impart the desired lubricity, and is compatiblewith the molding conditions can be employed. Some possible lubricantsinclude molybdenum disulfide (MOS₂), graphite fluoride (CF_(1.1)))_(n),silicone oils (such as polydimethylsiloxane and the like), fluorocarbonoils (such as perfluoropolyethers (Fomblin or Krytox) and the like),surfactants (such as FC430 commercially available from 3M, and thelike), petroleum oils, and the like, as well as reaction products andcombination comprising at least one of any of the foregoing lubricants.

[0027] If the lubricant is applied as a layer, the layer can bedeposited by any technique capable of attaining the desired lubricityand thickness uniformity. Some possible techniques include spin coating,spraying, vapor deposition (e.g., chemical vapor deposition, plasmaenhanced chemical vapor deposition, and the like), electrodepositioncoating, meniscus coating, spray coating, extrusion coating, and thelike, as well as combinations comprising at least one of thesetechniques. Typically, if a layer is employed, the layer preferably hasa sufficient thickness to reduce the coefficient of friction between thelayer and the molding equipment to about 0.5 or less. For example, thelayer can have a thickness of about 1 micrometer or less, with athickness of about 0.5 micrometers or less preferred, and a thickness ofabout 0.1 micrometers or less especially preferred. If the lubricant iscombined into the managed heat transfer layer, less than or equal toabout 60 weight percent (wt %) lubricant can be employed, with less thanor equal to about 50 wt % preferred, and less than or equal to about 40wt % lubricant especially preferred, based upon the total weight of themanaged heat transfer layer. It is further preferred to employ greaterthan or equal to about 5 wt % lubricant, with greater than or equal toabout 10 wt % lubricant preferred, based upon the total weight of themanaged heat transfer layer.

[0028] Although random imperfections and non-uniform thickness in themanaged heat transfer layer are not desirable, it can be advantageous toimpart areas of increased friction on the surface of the managed heattransfer layer to enhance the ability of the molding equipment to retainthe stamper in place. Preferably, the areas of increased thickness havea sufficiently small surface roughness (e.g., non-uniform thickness) toprevent translation of the roughness to the article, while enhancingstamper retention in the molding equipment. Generally, a roughness ofless than or equal to about 0.50 μm is employed, with a roughness ofless than or equal to about 0.40 μm preferred, and less than or equal toabout 0.30 μm especially preferred, as measured from a plane of saidmanaged heat transfer surface. It is also preferred to employ aroughness of greater than about 0.20 μm, with a roughness of greaterthan about 0.25 μm more preferred. Note, such roughness will stillretain a substantially uniform thickness (e.g., a thickness variation ofless than about 5%). It is especially preferred to increase thecoefficient of friction to about 0.5 or so, with a coefficient offriction of about 1.0 or greater more preferred in the areas of contactwith the mold, e.g., areas of vacuum contact.

[0029] Another issue that can increase the coefficient of friction andthus abrasion between the mirror block and the managed heat transferlayer is static charge buildup between the layers. A mirror block willoften be coated with a hard, electrically insulating coating such assilicon nitride or diamond. Managed heat transfer layers can also beelectrically non-conductive if made out of unfilled or undoped plasticcoatings. Slight movement between the layers during mold operation canresult in static charge build-up between them since the charge is notable to dissipate (or flow) through the insulator coatings to a neutralsurface. This static charge increases the coefficient of friction,accelerating wear of both surfaces.

[0030] Coating of the managed heat transfer layer and/or mirror blockwith a static dissipating material such as an alkyl quaternary ammoniumcompound would allow the static charge to flow to a neutral sitereducing the coefficient of friction. Alternatively, if the managed heattransfer coating was inherently electrically conductive, such as a lowthermal conductive metal alloy, or a graphite filled or doped plasticmaterial, coating with an electrically conductive material would not beas beneficial. Combining a lubricant with an electrically conductivecompound for coating on non-electrically conductive managed heattransfer layer and mirror surfaces is preferred. For example,incorporating graphite fibers into the polymer used for forming themanaged heat transfer layer would provide an electrically conductivecoating. Application of MoS₂ on the surface of the graphite fiber filledpolymer will provide a lubricated, electrically conductive managed heattransfer layer.

[0031] After prolonged use of the managed heat transfer layer in themolding equipment, it is possible that the surface modifications andlubricity at the surface has degraded enough such that the stamper nolonger produces good quality disks. If this occurs, it is possible torepolish and/or surface treat the managed heat transfer layer againusing the same techniques described above to render the stamper usefulin subsequent data storage media (e.g., CD disks and the like)production.

[0032] Referring to the FIG. 1, a sectional side view of an injectionmold 10 including a managed heat transfer layer 12 and a pair of moldhalves 14 of high thermally conductive material forming a mold cavity 16is illustrated. Thermally insulative is meant to include materialshaving coefficients of thermal conductivity less than that of thestamper employed in the molding press. Generally, a nickel stamper isused which has a thermal conductivity of about 92 watts per meter Kelvin(W/m·K). Any material having thermal conductivity lower than that of thenickel stamper, such as thermal conductivity of less than or equal toabout 50 W/m·K would slow down the transfer of heat from the moldchamber to the mold press. Thermally conductive is meant to includematerials having coefficients of thermal conductivity greater than orequal to about 100 W/m·K.

[0033] Cooling lines 18, such as copper pipes, are provided in each moldhalf 14 for receiving a cooling fluid to reduce cycle time. At least onecompact disc or optical disc stamper 20 is positioned in the mold cavity16 as shown and secured therein in a known manner. The stamper 20 has agrooved or pitted surface 22 carrying information. If desired, a secondstamper 23, optionally comprising surface features on all, part, or noneof its surface, can additionally be positioned in mold cavity 16. Forpurposes of example, a smooth surface of the stamper is represented byportion 19 and a grooved or pitted surface of the stamper for carryinginformation is represented by portion 17. Typically, the stampercomprises electroplated nickel, chrome, titanium, copper, siliconhowever, other materials, metals, and the like, as well as alloyscomposites, cermets, and combinations comprising at least one of theforegoing materials can be employed. Meanwhile, the mold halvestypically comprise a ferrous material such as steel or the like,although other metals and/or alloys can similarly be employed.

[0034] Each mold half 14 can have a surface 21 disposed adjacent to themanaged heat transfer layer 12 that optionally includes asurface-finished layer (e.g., lubricant layer, polished surface, lappedsurface, and the like) 12S. The managed heat transfer layer 12 may be inthe form of a single thin insulating layer or multilayer insulatedstructure that can be fabricated from low thermally conductive materialssuch as thermoplastic materials, thermoset materials, plasticcomposites, porous metals, ceramics, and low-conductivity metal alloys,and metal oxides, as well as cermets, composites, reaction products, andcombinations comprising at least one of the foregoing materials.Possible metal materials include Nichrome (60% Ni and 20% Cr), Invar(64% Fe, 36% Ni), titanium, and the like. Possible ceramics includealuminum oxide, silicon oxide, aluminum nitride, and silicon carbide,and the like. Possible plastics include amorphous, crystalline, and/orsemicrystalline materials and reaction products and combinationscomprising at least one of the foregoing materials. Typical plasticsused for forming the managed heat transfer layer comprise polyimides,polyamideimides, polyamides, polysulfone, polyethersulfone,polytetrafluoroethylene, and polyetherketone, as well as composites,reaction products, and combinations comprising at least one of theforegoing materials and/or a plastic set forth below. The plastic istypically applied in uncured form (e.g., as a polyamic acid in the caseof a polyimide or polyamideimide) and subsequently heat cured.Preferably, the managed heat transfer layer is flexible film such as apolyimide film manufactured under the trademark KAPTON.

[0035] Generally, the managed heat transfer layer has a thickness thatis greater than about 0.1 mil (0.00254 millimeters (mm)), with greaterthan about 0.5 mils (0.0127 mm) preferred. It is further preferred tohave a thickness of less than about 5 mils (0.127 mm), with less thanabout 2 mils (0.0508 mm) more preferred.

[0036] In addition to the above materials, the managed heat transferlayer can comprise fillers. The fillers should have a size and geometrythat does not interfere with the primary and secondary surface features.Some possible filler include glass, aluminum silicate (AlSiO₃), bariumsulfate (BaSO₄), alumina (Al₂O₃), silica, and the like, or a layer offilled polyimide resin coated with a layer of non-filled polyimideresin, as well as combinations and layers, comprising at least one ofthe foregoing fillers.

[0037] During molding, molten plastic resin 44 can be injected into themold cavity 16 via a sprue bushing 36 and a sprue 38. Possible plasticsinclude amorphous, crystalline, and/or semicrystalline materials andreaction products and combinations comprising at least one of theforegoing materials. For example the plastic can comprise: polyvinylchloride, polyolefins (including, but not limited to, linear and cyclicpolyolefins and including polyethylene, chlorinated polyethylene,polypropylene, and the like), polyesters (including, but not limited to,polyethylene terephthalate, polybutylene terephthalate,polycyclohexylmethylene terephthalate, and the like), polyamides,polysulfones (including, but not limited to, hydrogenated polysulfones,and the like), polyimides, polyether imides, polyether sulfones,polyphenylene sulfides, polyether ketones, polyether ether ketones, ABSresins, polystyrenes (including, but not limited to, hydrogenatedpolystyrenes, syndiotactic and atactic polystyrenes, polycyclohexylethylene, styrene-co-acrylonitrile, styrene-co-maleic anhydride, and thelike), polybutadiene, polyacrylates (including, but not limited to,polymethylmethacrylate, methyl methacrylate-polyimide copolymers, andthe like), polyacrylonitrile, polyacetals, polycarbonates, polyphenyleneethers (including, but not limited to, those derived from2,6-dimethylphenol and copolymers with 2,3,6-trimethylphenol, and thelike), ethylene-vinyl acetate copolymers, polyvinyl acetate, liquidcrystal polymers, ethylene-tetrafluoroethylene copolymer, aromaticpolyesters, polyvinyl fluoride, polyvinylidene fluoride, polyvinylidenechloride, tetrafluoroethylene fluorocarbon polymers (e.g., Teflons). Theplastic may also or alternatively comprise thermosetting resins such asepoxy, phenolic, alkyds, polyester, polyimide, polyurethane, mineralfilled silicone, bis-maleimides, cyanate esters, vinyl, andbenzocyclobutene resins. Additionally, the plastic may comprise blends,copolymers, mixtures, reaction products and composites comprising atleast one of the foregoing thermoplastics and/or thermosets. Forexample, “Nylon 6” or “Nylon 12” or “Nylon 6,6” which are commerciallyavailable, can be employed.

[0038] Various thermoplastic materials may be used such as polyamide,for example, “Nylon 6” or “Nylon 12” or “Nylon 6,6” which arecommercially available”; and other polymers such as polyesters,poly(butylene terephthalate) (PBT), poly(ethylene terephthalate) (PET),and PBT with soft ether linkages formed of polycarbonate and methylene,polyether ketones, polyetherimides, polylactams, polypropylenes,polyethylenes, polystyrene (PS), styrene acrylonitrile, acrylonitrilebutadiene terpolymers, polyphenylene oxide/polystyrene and polyphenyleneoxide/nylon and high impact styrenes filled or unfilled and blendsthereof.

[0039] Heat from the plastic 44 is absorbed through the stamper 20. Themanaged heat transfer layer preferably prevents quick cooling of theplastic 44, regulating heat transfer. This results in a hot plasticsurface at the interface between the stamper 20 and the plastic 44 for ashort time period. The managed heat transfer layer 12 and the stamper 20cooperate to provide the desired surface quality to the produced article(e.g., data storage media).

EXAMPLE 1

[0040] Ni stamper (commercially available from Technicolor,Ruckersville, Va.), for manufacture of CD-ROM, was cleaned usingpropanol solvent and clean-room Texwipe cloth. Approximately 10 gramspolyimide solution (Dupont, P12611) was dispensed on the center of thestamper and it was spun at 800 revolutions per minute (rpm) for 30seconds to obtain a uniform coating on the stamper backside surface. Thecoating was baked in an oven with ramped temperature from 100° C. to400° C. over 4 hours and held at 400° C. for 1 hour to obtain a finalcured film thickness of approximately 24 μm. After curing, the frontside having information of the stamper was protected by application ofNitto tape, then the other side was subjected to a surface treatment byusing Model P-127 High Quality Micro Sander lapping machine(commercially available from Record Products of America, Hamden, Conn.)with a fine paper (9 micrometer Imperial Lapping Paper commonlyavailable from 3M®). Preliminary surface roughness (Ra) for the curedpolyimide was 107 nanometers (nm), after polishing it was reduced to 48nanometers.

EXAMPLE 2

[0041] A Ni stamper having a polyimide layer was prepared as inExample 1. With the front side having information of the stamperprotected, the other side was subjected to a surface treatment by usingan etching of 2 wt % potassium hydroxide dissolved in and 80/20 mixtureof ethanol and water which will remove about 1 micrometer/minute of thepolyimide coating. After etching for 1 minute, the modulus for thepolyimide surface was about 100 Kpsi vs. 400 Kpsi for that of the bulk.

EXAMPLE 3

[0042] A Ni stamper having a polyimide layer was prepared as inExample 1. With the front side having information of the stamperprotected, the other side was subjected to plasma treatment by using areactive ion etching system (Anelva, Model 506 Parallel Plate System) inwhich CHF₃ gas at a flow rate of 200 standard cubic centimeters (sccm)at a pressure of 500 milliTorr using an rf frequency of 13.56 megahertz(MHz) and 300 watts (W) power. Using these conditions, a fluorinatedcarbon layer was deposited on the polyimide layer at a deposition rateof approximately 500 angstroms/minute.

EXAMPLE 4

[0043] On a Ni stamper substrate, approximately 10 grams polyimidesolution (Dupont, P12611) was dispensed in the center. The stamper wasspun at 800 rpm for 30 seconds to obtain a uniform coating on thestamper backside surface. The coating was baked in an oven with rampedtemperature from 100° C. to 400° C. for over 4 hours and held at 400° C.for 1 hour to obtain a final cured film thickness of approximately 24μm. After cure, the front information side was protected with Nitto tapeand the backside managed heat transfer polymer layer was hand polishedto remove film defects due to particles and bubbles. A 3M® hard rubbersanding block was used with 12,000 grit Micro Mesh cushioned abrasivesand paper commercially available from Micro-Surface Finishing Products,Inc., Wilton, Iowa. Preliminary surface roughness for the curedpolyimide was 107 nanometers, after polishing it was reduced to 24nanometers.

[0044] In the above examples, particles and small bubbles that can existin the non-treated managed heat transfer layers were removed. Also,dimples and flaws were removed to result in a local flatness of lessthan about 50 nm. Further, when installing the stampers prepared in theexamples to a mold, injecting plastic (e.g., polycarbonate and the like)to the mold to form an article (e.g., optical discs, and various otherarticles requiring a smooth surface), imperfections on the surface ofthe storage media was reduced. Imperfections on the optical diskcommonly consist of dimples (caused by bubbles or particles on themanaged heat transfer layer) or microwaviness (caused by non-uniformcoating of the managed heat transfer layer) both of which can interferewith play back of information on the disk. Surface treatments of themanaged heat transfer layer removes these imperfections and allows muchlonger lifetime in the mold apparatus due to reduced abrasion during themolding process.

[0045] While the invention has been described with reference to anexemplary embodiment, it will be understood by those skilled in the artthat various changes maybe made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

What is claimed is:
 1. A method for manufacturing an article,comprising: disposing a managed heat transfer layer in operablecommunication with a second surface of a stamper, wherein a firstsurface of said stamper comprises surface features, wherein an exposedsurface of said managed heat transfer layer has been altered by a methodselected from the group consisting of chemically, mechanically, or acombination thereof; disposing the stamper in a mold with at least aportion of said exposed surface disposed in operable communication witha mold half; injecting a molten plastic into said mold; cooling theplastic to form said data storage media; and releasing said data storagemedia from said mold.
 2. The method of claim 1, further comprisingforming a thickness of said managed heat transfer layer having avariation of less than about 5%.
 3. The method of claim 2, whereinforming said substantially uniform thickness further comprises surfacelapping said exposed surface.
 4. The method of claim 3, wherein saidthickness varies less than about 3%.
 5. The method of claim 4, whereinsaid thickness varies less than about 1%.
 6. The method of claim 5,wherein said thickness varies less than about 0.5%.
 7. The method ofclaim 2, wherein said lapping further comprises grinding with sand paperhaving a grit particle size of less than or equal to about 9micrometers.
 8. The method of claim 1, wherein said chemically alteredexposed surface comprises a polymer chain length shorter than anon-chemically altered portion said managed heat transfer layer.
 9. Themethod of claim 1, wherein said managed heat transfer layer comprises amaterial selected from the group consisting of thermoset materials,plastics, porous metals, ceramics, low-conductivity metal alloys, andcermets, composites, reaction products, and combinations comprising atleast one of the foregoing materials.
 10. The method of claim 9, whereinsaid material is selected from the group consisting of polyimides,polyamideimides, polyamides, polysulfone, polyethersulfone,polytetrafluoroethylene, polyetherketone, and composites, reactionproducts, and combinations comprising at least one of the foregoingmaterials.
 11. The method of claim 1, wherein said managed heat transferlayer further comprises a lubricant component either incorporated intothe managed heat transfer layer or placed on its surface.
 12. The methodof claim 11, wherein lubricant is selected from the group consisting ofmolybdenum disulfide (MOS₂), graphite fluoride (CF_(1.1)))_(n), andreaction products and combinations comprising at least one of theforegoing lubricants.
 13. The method of claim 11, wherein said managedheat transfer layer comprises about 5 wt % to about 60 wt % of saidlubricant, based upon the total weight of the managed heat transferlayer.
 14. The method of claim 13, wherein said managed heat transferlayer comprises about 5 wt % to about 50 wt % of said lubricant, basedupon the total weight of the managed heat transfer layer.
 15. The methodof claim 14, wherein said managed heat transfer layer comprises about 10wt % to about 40 wt % of said lubricant, based upon the total weight ofthe managed heat transfer layer.
 16. The method of claim 11, whereinsaid lubricant is in the form of a layer disposed on said exposedsurface.
 17. The method of claim 16, wherein said lubricant layer has athickness of less than or equal to about 1 micrometer.
 18. The method ofclaim 17, wherein said thickness is about 0.01 micrometers to about 0.10micrometers.
 19. The method of claim 1, wherein said exposed surfacefurther comprises an area of roughness where said exposed surfaceoperably communicates with said mold, wherein said roughness is lessthan or equal to about 0.50 micrometers, as measured from a plane ofsaid managed heat transfer surface.
 20. The method of claim 19, whereinsaid roughness is about 0.20 micrometers to about 0.40 micrometers. 21.The method of claim 20, wherein said roughness is about 0.25 micrometersto about 0.30 micrometers.
 22. The method of claim 1, wherein acoefficient of friction of greater than or equal to about 0.50 exists inan area of physical contact between said managed heat transfer layer andsaid support.
 23. The method of claim 1, wherein said article is a datastorage media.
 24. A molding apparatus for producing a data storagemedia comprising: a stamper comprising a managed heat transfer layer,wherein a first surface of said stamper comprises surface features, andwherein an exposed surface of said managed heat transfer layer has beenaltered by a method selected from the group consisting of chemically,mechanically, or a combination thereof, and has a thickness variation ofless than about 5%; and a support for receiving the stamper by operablecommunication with said managed heat transfer layer.
 25. The moldingapparatus of claim 24, wherein said managed heat transfer layercomprises a material selected from the group consisting of thermosetmaterials, plastics, porous metals, ceramics, low-conductivity metalalloys, and cermets, composites, reaction products, and combinationscomprising at least one of the foregoing materials.
 26. The moldingapparatus of claim 25, wherein said material is selected from the groupconsisting of polyimides, polyamideimides, polyamides, polysulfone,polyethersulfone, polytetrafluoroethylene, polyetherketone, andcomposites, reaction products, and combinations comprising at least oneof the foregoing materials.
 27. The molding apparatus of claim 24,wherein said managed heat transfer layer further comprises a lubricant.28. The molding apparatus of claim 27, wherein lubricant is selectedfrom the group consisting of molybdenum disulfide (MOS₂), graphitefluoride (CF_(1.1)))_(n), and reaction products and combinationscomprising at least one of the foregoing lubricants.
 29. The moldingapparatus of claim 27, wherein said managed heat transfer layercomprises about 5 wt % to about 60 wt % of said lubricant based upon thetotal weight of the managed heat transfer layer.
 30. The moldingapparatus of claim 29, wherein said managed heat transfer layercomprises about 5 wt % to about 50 wt % of said lubricant based upon thetotal weight of the managed heat transfer layer.
 31. The moldingapparatus of claim 30, wherein said managed heat transfer layercomprises about 10 wt % to about 40 wt % of said lubricant based uponthe total weight of the managed heat transfer layer.
 32. The moldingapparatus of claim 31, wherein said lubricant is in the form of a layerdisposed on said exposed surface.
 33. The molding apparatus of claim 32,wherein said lubricant layer has a thickness of less than or equal toabout 1 micrometer.
 34. The molding apparatus of claim 33, wherein saidthickness is about 0.01 micrometers to about 0.10 micrometers.
 35. Themolding apparatus of claim 24, wherein said exposed surface furthercomprises an area of roughness where said exposed surface operablycommunicates with said mold, wherein said roughness is less than orequal to about 0.50 micrometers as measured from a plane of said managedheat transfer surface.
 36. The molding apparatus of claim 35, whereinsaid roughness is about 0.20 micrometers to about 0.40 micrometers. 37.The molding apparatus of claim 36, wherein said roughness is about 0.25micrometers to about 0.30 micrometers.
 38. The molding apparatus ofclaim 24, further comprising a coefficient of friction of greater thanor equal to about 0.50 in an area of physical contact between saidmanaged heat transfer layer and said support.
 39. A method for producinga stamper, comprising: forming a nickel plated substrate having desiredsurface features on one side; disposing a managed heat transfer layer ona second side of said substrate; forming a thickness of said managedheat transfer layer having a variation of less than about 5%; andaltering an exposed surface of said managed heat transfer layer, whereinsaid altering is by a method selected from the group consisting ofchemically altering, mechanically altering, or a combination thereof.40. The method of claim 39, wherein said chemically altering saidexposed surface further comprises reactive ion etching with a selectedfrom the group consisting of oxygen, chlorine, hydrochloric acid,fluorocarbons, nitrogen, nitrogen oxides, argon, boron trichloride,hydrogen, sulfur hexafluoride, and ions, reaction products, andcombinations comprising at least one of the foregoing gases.
 41. Themethod of claim 39, wherein chemically altering said exposed surfacefurther comprises exposing said exposed surface to an aqueous causticsolution.
 42. The method as in claim 41, wherein said aqueous causticsolution comprises potassium hydroxide.
 43. The method of claim 39,wherein forming said thickness further comprises surface lapping saidexposed surface.
 44. The method of claim 43, wherein said thicknessvaries less than about 3%.
 45. The method of claim 44, wherein saidthickness varies less than about 1%.
 46. The method of claim 45, whereinsaid thickness varies less than about 0.5%.
 47. The method of claim 43,wherein said lapping further comprises grinding with sand paper having aparticle size of less than or equal to about 5 micrometers.
 48. Themethod of claim 40, wherein chemically altering said exposed surfacefurther comprises shortening a polymer chain length of plastic disposedat said exposed surface.
 49. The method of claim 39, wherein saidmanaged heat transfer layer comprises a material selected from the groupconsisting of thermoset materials, plastics, porous metals, ceramics,low-conductivity metal alloys, and cermets, composites, reactionproducts, and combinations comprising at least one of the foregoingmaterials.
 50. The method of claim 49, wherein said material is selectedfrom the group consisting of polyimides, polyamideimides, polyamides,polysulfone, polyethersulfone, polytetrafluoroethylene, polyetherketone,and composites, reaction products, and combinations comprising at leastone of the foregoing materials.
 51. The method of claim 39, wherein saidmanaged heat transfer layer further comprises a lubricant.
 52. Themethod of claim 49, wherein lubricant is selected from the groupconsisting of molybdenum disulfide (MOS₂), graphite fluoride(CF_(1.1)))_(n), and reaction products and combinations comprising atleast one of the foregoing lubricants.
 53. The method of claim 49,wherein said managed heat transfer layer comprises about 5 wt % to about60 wt % of said lubricant based upon the total weight of the managedheat transfer layer.
 54. The method of claim 53, wherein said managedheat transfer layer comprises about 5 wt % to about 50 wt % of saidlubricant based upon the total weight of the managed heat transferlayer.
 55. The method of claim 54, wherein said managed heat transferlayer comprises about 10 wt % to about 40 wt % of said lubricant basedupon the total weight of the managed heat transfer layer.
 56. The methodof claim 39, further comprising forming a lubricant layer on saidexposed surface.
 57. The method of claim 56, wherein said lubricantlayer has a thickness of less than or equal to 1 micrometer.
 58. Themethod of claim 57, wherein said thickness is about 0.01 micrometer toabout 0.10 micrometer.
 59. The method of claim 39, wherein said exposedsurface further comprises an area of roughness where said exposedsurface operably communicates with said mold, wherein said roughness isless than or equal to about 0.50 micrometers, as measured from a planeof said managed heat transfer surface.
 60. The method of claim 59,wherein said roughness is about 0.20 micrometers to about 0.40micrometers.
 61. The method of claim 60, wherein said roughness is about0.25 micrometers to about 0.30 micrometers.